The man page at http://xmonad.org/manpage.html says:
"When running with multiple monitors (Xinerama), .... If you switch to
a workspace which is currently visible on another screen, xmonad
simply switches focus to that screen."
In the current darcs version (and in version 0.3), that isn't true.
The behavior can be made to agree with the man page by changing
W.greedyView to W.view in Config.hs. Or is the man page out of date?